Pixelmon Mod

when i try to go into a portal is says that the version is null and it needs version 8.1.2. that is the version that I downloaded, but it keeps saying it is null. I was able to get the same file to work fine on my two PC's but it won't work on my Mac.

Null implies an incorrect installation, mods in the wrong place/not loading properly. If you're having trouble installing it might be better to use a modpack launcher instead, we have a guide on https://pixelmonmod.com/wiki/Visual_guide_to_installing_Pixelmon